Amorphous-nanocrystalline-microcrystalline coatings and methods of production thereof

Abstract

This invention relates to thermally sprayed coatings having an amorphous-nanocrystalline-microcrystalline composition structure, said thermally sprayed coating comprising from about 1 to about 95 volume percent of an amorphous phase, from about 1 to about 80 volume percent of a nanocrystalline phase, and from about 1 to about 90 volume percent of a microcrystalline phase, and wherein said amorphous phase, nanocrystalline phase and microcrystalline phase comprise about 100 volume percent of said thermally sprayed coating. This invention also relates to methods for producing the coatings, thermal spray processes for producing the coatings, and articles coated with the coatings. The thermally sprayed coatings of this invention provide enhanced wear and corrosion resistance for articles used in severe environments (e.g., landing gears, airframes, ball valves, gate valves (gates and seats), pot rolls, and work rolls for paper processing).

The invention claimed is: 
     
       1. A thermally sprayed coating having an amorphous-nanocrystalline-microcrystalline composition structure, said thermally sprayed coating comprising from about 1 to about 95 volume percent of an amorphous phase, from about 1 to about 80 volume percent of a nanocrystalline phase, and from about 1 to about 90 volume percent of a microcrystalline phase, and wherein said amorphous phase, nanocrystalline phase and microcrystalline phase comprise about 100 volume percent of said thermally sprayed coating, in which (i) the nanocrystalline phase comprises discrete particles, wherein said particles comprise one or more grains having a nanocrystalline structure, and wherein said nanocrystalline structure comprises a grain size of less than about 100 nanometers; and (ii) the microcrystalline phase comprises discrete particles, wherein said particles comprise one or more grains having a microcrystalline structure, and wherein said microcrystalline structure comprises a grain size of from about 100 nanometers to less than about 1000 nanometers, wherein the distance between said nanocrystalline phase particles is no greater than about 0.5 mils, the distance between said microcrystalline phase particles is no greater than about 0.5 mils, and the distance between said nanocrystalline phase particles and said microcrystalline phase particles is no greater than about 0.5 mils. 
     
     
       2. A thermally sprayed coating having an amorphous-nanocrystalline-microcrystalline composition structure, said thermally sprayed coating comprising from about 5 to about 90 volume percent of said amorphous phase, from about 5 to about 75 volume percent of said nanocrystalline phase, and from about 5 to about 80 volume percent of said microcrystalline phase, wherein said amorphous phase, nanocrystalline phase and microcrystalline phase comprise about 100 volume percent of said thermally sprayed coating. 
     
     
       3. The thermally sprayed coating of  claim 2  which has a thickness of not greater than about 120 mils. 
     
     
       4. An article coated with the thermally sprayed coating of  claim 2 . 
     
     
       5. The article of  claim 4  which is coated by a frequency pulse detonation gun. 
     
     
       6. The article of  claim 5  wherein the detonation gun operates at an equivalence ratio of from about 1 to about 3 and a firing frequency of from about 5 to about 200 Hz. 
     
     
       7. The article of  claim 4  which is a material selected from the group consisting of steel, Ni-, Co-, Ti-based alloys, graphite, aluminum, copper. 
     
     
       8. The article of  claim 4  selected from the group consisting of landing gears, airframes, ball valves, gate valves, pot rolls, and work rolls for paper processing. 
     
     
       9. A thermally sprayed coating having an amorphous-nanocrystalline-microcrystalline composition structure, said thermally sprayed coating comprising from about 1 to about 95 volume percent of an amorphous phase, from about 1 to about 80 volume percent of a nanocrystalline phase, and from about 1 to about 90 volume percent of a microcrystalline phase, and wherein said amorphous phase, nanocrystalline phase and microcrystalline phase comprise about 100 volume percent of said thermally sprayed coating, wherein the coating comprises a cermet, metal alloy or alloy-oxide ceramic coating, in which the cermet coating comprises WCM where M is Cr, Co, Ni, CrC, NiCr or any combination thereof, the metal alloy coating comprises FeM′M″ where M′ is Cr, Ni, Co or any combination thereof, and M″ is C, Si, B, P or any combination thereof, and the alloy-oxide ceramic coating comprises M′″CrAlY+X where M′″ is Ni, Co or Fe or any combination thereof, and X is fine oxide ceramic dispersant particles, in which the fine oxide ceramic dispersant particles comprise fine alumina dispersant particles, and said alloy-oxide ceramic coating optionally includes the addition of Pt, Ta, Hf, Re, singularly or in combination.